1. Field of the Invention
The present invention relates to a text conversion apparatus capable of relieving inputting load, and more particularly to apparatus for text conversion which is adapted to enter an input text such as letters, e.g. Japanese letters (kana), to be converted to an output text, such as a character or characters (string of characters), e.g. kanji or Chinese characters, to be transmitted and accurately list a candidate or candidates for conversion to be selected to thereby be converted to the character or characters. The present invention also relates such a method therefor.
2. Description of the Background Art
There have so far been proposed apparatus for moderating the load of the operation in inputting a string of letters to be converted. In apparatus such as personal computers, word processors, mobile phones or PDAs (Personal Digital Assistants), such an inputting method is used in which keys, e.g. alphanumeric keys, allocated to letters are manipulated to input letters to be converted in order to get a desired string of characters. For example, when such letter keys are depressed to input letters required for being converted to a character and a conversion key is then depressed, at least one character or a character string corresponding to the input letters is taken out from a word-finder, i.e. a dictionary, and displayed on a monitor unit of the apparatus. With those apparatus, when desired one of the characters or character strings is selected and an entry key is depressed, the intended character or character string may promptly be input with such a small volume of key operations. In particular, a small-sized information processing terminal device, having its input/output interface made smaller in size, tends to be lowered in its operational performance in proportion to the configuration for inputting and displaying character strings. Thus, in the small-sized information processing terminal device, there may be cases where it is a crucial designing requirement to decrease the load in the inputting operation.
Japanese patent laid-open publication No. 768/1988 teaches an apparatus for formulating Japanese sentences. This apparatus for formulating Japanese sentences interprets an input clause and uses a knowledge database to predict a clause following thereto to present a so predicted clause.
Japanese patent laid-open publication No. 114817/1997 teaches a text input apparatus, which predicts, when a character string is input, a conversion candidate that may follow the input character string to present the predicted string. This text input apparatus presents, among the conversion candidates, a predetermined number of candidates selected in the latest order of the preparation time, such as to relieve the load of the inputting operation.
U. S. patent application publication No. US 2003/0233615 A1 to Morimoto et al., discloses an information processing apparatus, in which, when a subject for conversion, such as letters, is processed with one or more conversion candidates, the subject for conversion is correlated with time information to thereby raise the efficiency for processing for conversion. In this information processing apparatus, when a Japanese letter, such as a kana letter, corresponding to “o” is input and the conversion key is depressed, a string of letters “ohayo” or “oyasumi” is associatively and preferentially displayed on the monitor in dependent on whether the current time is morning or night, respectively.
In Japanese patent laid-open publication No. 2004-145418, there is disclosed an email formulating apparatus, in which the user inputs relevant information such as a destination or addressee in a database in advance and the specifications for a message input display screen are adapted depending on the input address to thereby prevent transmission of an email of inappropriate content or an email to a wrong address. With this email formulating apparatus, the kana-kanji conversion level or a mode of checking the wording, as applied to inputting a message, is appropriately adapted using such relevant information.
It should be noted that, when a character string to be transmitted to a destination of transmission, such as of an email, chat, messenger or electronic bulletin board, is entered, the above apparatus may sometimes use particular character strings or wording styles, depending on social relationships, such as business or intercourse relationships, with the destination of transmission. In such a case, when a letter string containing at least one letter is entered as a subject for conversion, if the above apparatus properly presents a string of characters, which may prove a conversion candidate, in dependence upon a particular destination of transmission, the apparatus then can select an intended character string with ease. This may lessen the load involved in the inputting operation.
However, the apparatus disclosed by the Japanese '768 or '817 publication indicated above is merely adapted to use an input letter string to extract conversion candidates. These apparatus fail to take into account the relationship with the destinations of transmission. Hence, these apparatus are unable to optimize the processing for conversion depending on the destination of transmission.
In the information processing apparatus, disclosed, by Morimoto et al., the processing for conversion may be improved in efficiency only for letter strings pertinent to time information, such as sentences for salutation. This apparatus is unable to optimize the processing for conversion depending on the destination of transmission and to moderate the load on the inputting operation.
In the email formulating apparatus, described in Japanese '418 publication, it is possible to adapt, depending on a destination of transmission, the condition for conversion pertinent to the wording check mode or to the level of kana-kanji conversion in inputting a letter string as a subject of transmission to prevent transmission of the character string of inappropriate content.
However, this email formulating apparatus after all selects one of predetermined conditions for conversion depending on a destination of transmission. It is thus not possible with the email formulating apparatus to present a character string that may prove to be a candidate for conversion appropriately for a particular destination of transmission. If the apparatus is used for selecting a condition for conversion, relevant information concerning a destination of transmission needs to be pre-input or set. It is thus not easy for the email formulating apparatus of the Japanese '418 publication to optimize the processing for conversion depending on a destination of transmission.
With the above prior-art apparatus, disclosed by the Japanese '768, '817 and '418 publications and Morimoto et al., it may be possible to optimize the processing for conversion. It may sometimes occur, however, that abusive use of the learning or prediction function of the text input device may lead to conjecturing how the information thus inputted is. If an arbitrary letter string is input as a subject for conversion to these apparatus to convert the input letter string, then character strings, which may prove to be candidates for conversion pertinent to the subject for conversion, are taken out from the learning functional memory, that is, a word-finder or a dictionary, to be displayed on the monitor screen.
In particular, since the learning memory has stored therein the information including the past conversion history, the information input in the past may be guessed from the character strings presented for the subject of conversion as being the possible candidates for conversion.